This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this proposed project is to compare the efficacy, as measured primarily by sputum weight, of sine waveform HFCWO using higher inflation pressures combined with low and high oscillator frequencies to lower inflation pressures combined with mid-range oscillator frequencies in clinically stable CF patients with mild to moderate lung disease.